The subject matter herein relates generally to pressing devices, and more particularly, to tool head assemblies for pressing devices.
Pressing devices are employed in numerous applications to provide a user with a desired mechanical advantage. One exemplary application is in crimping tools used for making crimping connections, such as crimping terminals onto conductors. Another exemplary application is in cutting tools where the tool enables the user to apply a relatively large amount of force or pressure. In enabling such operations, it is generally desirable to provide a tool that can perform the desired operations, and is manageable as well. The pressing devices typically include a work head having tooling appropriate for the particular application, and an actuator coupled to the work head for driving the tooling. Hydraulic mechanisms are often employed in tool actuators. For example, the work head typically includes a fixed die and movable die that is hydraulically driven towards the fixed die to perform an operation. However, in some embodiments, the work head may have more than one movable die that are movable toward one another. The actuator includes a hydraulic pump that is operated to either directly or indirectly drive the movable die of the work head.
Some current pressing devices have work heads with tooling that simply close and open. For the example of a crimping tool, the terminal must be positioned and gripped in the proper location adjacent to the crimp tooling. If the tooling does not have a terminal locator, in order to grip the terminal, the tooling is advanced or closed and the operator must stop exactly when the movable die just touches the terminal. If the movable die is advanced too far, the terminal is already being crimped and it is difficult to insert a wire into the partially crimped terminal. With this type of pressing device, there is the advantage that the crimp terminal is immediately free when the jaws open.
One known design provided an improvement with tooling that is spring loaded closed. U.S. Pat. No. 5,730,022 shows one such embodiment. To use this type of tooling, the movable die must be manually moved apart to load the terminal. The spring loaded movable die is then released to hold the terminal, at which time the actuator could be actuated and the entire cycle completed without needing to stop the actuator at a specific point to grip the terminal. However, spring loaded closed type of pressing devices are not without disadvantages. For instance, the movable die of the tooling needs to be manually opened against the spring in order to release the crimped terminal. This extra process step adds time and complexity to the operation of the pressing device.
Other known designs are shown in U.S. Pat. No. 6,718,870 and U.S. Pat. No. 7,421,877. The movable die of the '870 and '877 pressing devices are jogged toward the fixed die of the tooling via the tool control trigger until the terminal is gripped. The pressing device provides a spring loaded portion of travel so that the crimp does not begin immediately when the tooling touches the terminal. However, the design of the '870 and '877 pressing device is not without problems. For example, it is still possible to close the tooling too far to get the wire in the terminal. Additionally, the tool stroke of the pressing device is made longer to take up the extra stroke of the spring loaded portion of stroke. Thus, with this pressing device design, it is difficult and time consuming to grip the terminal.